Although the general template for locomotor limb movements is located within the spinal cord of vertebrates, there is still some debate about the detailed structure of such a centrally contained locomotion generator. The experiments described herein are designed to test one model for such a template, the wave generator hypothesis. This theory states that there is a functional arrangement of motor neurons in the spinal cord of at least lower vertebrates which allows a simple stimulus passing down the cord to stimulate each motor neuron in turn, thus leading to the normal, stereotyped movement of the limbs. The animals used for the test will be a salamander, Ambystoma maculatum, and a teleost fish, Antennarius sp., which uses its modified pectoral and pelvic fins to walk on coral substrates in marine habitats. The test will consist of the following experiments on these species: (1) examine the total range of movement in the pectoral limb by means of film and dissections; (2) determine the pattern of muscle contractions of all limb muscles by electromyography; (3) map the motor neurons in the pectoral limb-moving segment of the spinal cord using horseradish peroxidase marking; (4) compare the map and muscle sequence patterns. The immediate objective of this research is to describe the neural control mechanisms for locomotion in two species of lower vertebrates. These studies will also lead to a better understanding of the evolution of terrestrial locomotion and will provide a model for interlimb coordination in all vertebrates, including humans.